The ‘nanonets’ are tiny scaffold-like structures that are built like a web. Wang’s nanonets are made with titanium disilicide, and coated with silicon particles that are built into a battery’s anode side. The completed structures offer faster, lighter and longer-lasting lithium-ion batteries.

The nanonet structures offer a unique structural strength, more surface area and greater conductivity, which produced a charge/re-charge rate five to 10 times greater than typical lithium-ion anode material, a common component in batteries for a range of consumer electronics. That kind of development would have a major impact on time to charge and the current needed to serve the charger.

The silicon doped titanium nanonets proved exceptionally durable, showing a negligible drop-off in capacity during charge and re-charge cycles. The researchers observed an average of 0.1% capacity fade per cycle between the 20th and the 100th cycles. That looks good, but a vehicle battery would need 365 times the number of years of expected life considered – 80 cycles extrapolated out to 2,000 or 4, 000 cycles would net about 12.5 tenths of a percent per 1000 cycles, thus if the rate holds into the high cycle rates, this is exciting technology – only about a 0.45% capacity loss per year. At that rate a nanonet structured battery could last 20 years before falling below 90% capacity.

Wang says in the Boston College press release, “As researchers pursue the next generation of re-chargeable lithium-ion battery technology, a premium has been placed on increased power and a greater battery life span. In that context, the Nanonet device makes a giant leap toward those two goals and gives us a superior anode material.”

Lithium-ion batteries are commonly used in consumer electronics devices. This type of rechargeable battery allows lithium ions to move from the anode electrode to the cathode when in use. When charged, the ions move from cathode back to the anode.

Wang’s team reports the structure and conductivity of the doped nanonets improved the ability to insert and extract lithium ions from the particulate silicon coating. Running at a charge/discharge rate of 8,400 milliamps per gram (mA/g) – which is approximately five to 10 times greater than similar devices – the specific capacity of the material was greater than 1,000 milliamps-hour per gram (mA-h/g). In comparison a typical laptop lithium-ion batteries are rated anywhere between 4,000 and 12,000 mA/h, meaning it would only take between four and 12 grams of the Nanonet anode material to achieve similar capacity. Wang’s work may be a new dawn for the weight and volume issue that lithium ion battery technology poses when size and mass are important values during engineering.

Wang said the capability to preserve the crystalline titanium silicon core during the charge/discharge process was the key to achieving the high performance of the Nanonet anode material. Additional research in his lab will examine the performance of the Nanonet as a cathode material.

Assuming the effort can be replicated, this is just round one, on the anode side alone, the questions of scale and cost are going to come up soon. There are several paths to more improvements, too. Most heartening is the materials are not costly and natively stable. If the technology can scale cheaply, the impact will be substantial – unless an even better design comes along.

Keep an eye out for the team’s cathode results; electron storage progress is accelerating.

Another great article, hit it out of the park. Can’t believe there’s this much original content in the green energy space on the Web.

Alph on
February 20, 2010 12:14 PM

@Jon, there are lots and lots of articles about how this is being chased after. I think the article underestimates yields, as several companies are claiming theoretical/eventual yields up to 20,000 gal/acre.